1. Field of the Invention
Military and civilian organizations have need of small, rugged, and low-cost glide and descent devices to carry sensor packages to obtain information and data in areas beyond their normal line-of-sight. These devices will carry various sensors: optical, audio, chemical, and biological, by way of example. A sensor suite can be tailored to gather specific information dependent upon the scenario. Possible scenarios are activities related to movement of personnel, vehicles, crowd control; atmospheric conditions; building, brush and forest fires progress; and agricultural crop conditions for pest and disease evaluation and control.
The present invention represents an enhanced state-of-the-art concept to provide a low cost, gun/mortar/rocket launched, quick deployable, controlled flight device for carrying a large variety of sensor devices into hazardous and non-hazardous areas for the purpose of data and information gathering and documentation. The device can fly in two modes. The first mode is unpowered, that is to fly as an autogyro. The second mode is powered flight using a power source to drive the rotating blades to provide lift for hover and ascent like a helicopter.
2. Description of Related Art
Typically gun launched payloads that require controlled descent (rate of fall) after ejection from the parent carrier (flight projectile) employ retardation devices such as parachutes, parafoils, ram-air devices or aircraft like devices such as folded fixed wing gliders. Parachutes, parafoils and ram-air devices are for the most part unguided and drift with the air currents as they descend with little or no means of steering. Aircraft devices may have onboard radio control units for guidance and control, but they depend on forward velocity to generate lift to maintain flight.
The device of the present invention is designed to withstand the high acceleration and spin rate environment of cannon and mortar launch systems. Maximum acceleration levels are 15,000 times the earth""s gravity with angular rates as high as 150,000 rad/sec2 for an artillery cannon launch. The invention must also withstand the spin rate of as much as 300 Hz. The device must also survive expulsion loads when ejected from the carrier body, as well as the initial air loads.
In order to fit into the cylindrical cavity of a projectile carrier body, a main rotor blade assembly and tail rotor assembly are designed to fold into a compact package. At a predetermined time the device is explosively expelled from the flight projectile and automatically unfolds and deploys to begin guided descent. The folded main rotor blades also serve as a canister to provide structural integrity and protection for the invention during launch and expulsion.
The present invention, not unlike existing rotary winged aircraft such as helicopters, obtains lift from the rotating main rotor blades. They are capable of controlled descent, hover and vertical ascent through use of these rotating blades and vertical flight control. Thus, forward velocity of the device is not required to maintain flight. The use of flight control and avionics may be required, and can be accomplished through the use of a radio control system or an auto pilot system, by way of example.
For the invention, the use of counter-rotating blades provides a means of roll torque control that must be provided by a tail rotor in existing systems. That is, the roll torque from each set of blades is canceled by the opposing rotation of the counter rotating blade system. These features are well known and have previously been demonstrated. Therefore, a tail rotor system is used in the present invention to provide horizontal directional control. The tail rotor system is designed to pivot about a tail boom to point the device and to control the direction of the down thrust flow from the main rotor blades to achieve horizontal translation, i.e., forward, rearward and sideways flight.
Some unique features of the present invention are in the characteristic of the folded design and mechanisms used to achieve the compactness, the simple blade pitch control mechanism used to achieve vertical flight controlled-descent (during unpowered flight) and hover and ascent (during powered flight), the tail rotor thrust control system for direction flight control, and the tail rotor pivot mechanism used to control the main rotor blade down wash thrust angle to achieve horizontal flight direction control.